JPH0547296Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a shoe for a drum brake.

[Conventional technology]

2. Description of the Related Art A leading trailing brake is an example of a conventional drum brake shoe in which a side surface of a lower end of a web forms a support portion that slidably abuts on an anchor fixed to a bucking plate. A leading trailing brake has a leading shoe and a trailing shoe arranged facing each other on a bucking plate, an expansion means such as a wheel cylinder is interposed between the upper ends of both shoes, and an anchor is placed between the lower ends of the shoes. It is a drum brake that has a basic structure in which the leading shoe has a self-boosting effect.

It is a leading trailing brake,
FIG. 3 shows a conventional shoe 11 used in a floating type, in which the lower end side surfaces of a pair of brake shoes are slidably abutted on both sides of an anchor fixed to a bucking plate. In the figure, 12 is a web, 13 is a rim, 14 is a lining, and arrow A indicates the rotation direction of a brake drum (not shown). Then, a support portion 12a formed on the side surface of the lower end of the web 12 comes into contact with one side surface of the anchor 15 fixed to a bucking plate (not shown), and an input portion 1 formed on the side surface of the upper end portion of the web 12.
A wheel cylinder (not shown) acts on 2b.

The shoe 11, particularly the leading shoe, wears out as the brake is used, as shown in FIGS. 4A to 4C. FIG. 4A shows the shoe 11 in the initial stage of use, and the lining 14 is in sliding contact with the inner circumferential surface 16 of the brake drum over almost the entire surface.

FIG. 4B shows the middle stage of use of the shoe 11.
is lowered due to its own weight, etc., and the contact point P of the support portion 12a with respect to the anchor 15 is gradually rising.
In the case of the leading shoe 11, a large surface pressure is generated on the anchor 15 side due to self-boosting action, and the shoe 11 gradually descends, so that the part of the lining 14 near the anchor 15 is pressed against the brake drum. in strong sliding contact with the inner circumferential surface 16 of
Uneven wear occurs significantly on the anchor 15 side of the lining 14.

FIG. 4C shows the later stage of use of the shoe 11, in which the shoe 11 drops significantly as the lining 14 wears down, the contact point P of the support portion 12a further rises, and the part of the lining 14 near the anchor 15 The uneven wear of the shoe 11 has increased, and the shoe 11 has reached a state where it is necessary to replace it.

[The problem that the idea attempts to solve]

However, in such a conventional drum brake shoe, when the lining wears out due to use of the brake, the anchor 1 of the lining 14
There is a unique problem in that the part near the wheel 5 is worn excessively compared to the part near the wheel cylinder, and this tendency is particularly noticeable in the shoe 11 which becomes the leading shoe during forward running. As a result, the shoe 11 must be replaced even though a sufficient amount of the lining 14 near the wheel cylinder remains.

For this reason, in the conventional shoe for drum brakes of this type, it is necessary to change the tension position of the lining 14 relative to the rim 13 or increase the tension angle, or to form an inclined surface with an adjusted angle on the side surface of the anchor 15. However, changing the tension position of the lining 14 or increasing the tension angle of the lining 14 does not actively suppress the uneven wear of the lining 14. Lining 14 in late use.
There is a limit to the effect of applying almost uniform wear to the entire surface, and in a configuration in which the side surface of the anchor 15 is inclined at an angle to suppress the descent of the shoe 11, the friction between the support portion 12a of the web 12 and the side surface of the anchor 15 is limited. It is substantially affected by coefficients, vibrations when the vehicle is running, etc., and it is virtually impossible to accurately follow the anchor 15 side of the lining 14 to prevent uneven wear.
4 was not able to provide almost uniform wear over the entire surface.

[Means to solve the problem]

This invention was made in view of such conventional problems, and its structure includes an arc-shaped rim with a lining fixed to the outer circumferential surface and a web formed on the inner circumferential surface, and the lower end of the web. In a shoe for a drum brake that forms a support portion whose side surface slidably abuts on an anchor fixed to a bucking plate, the upper end portion of the support portion is attached to the anchor when the lining is worn out by a predetermined amount. This is a shoe for drum brakes in which a protrusion for stopping is formed integrally with the web.

[Effect]

Thus, until the anchor side of the lining of the shoe wears out a predetermined amount, the support portion slides relative to the anchor in accordance with the wear, and braking force is obtained. When the anchor side of the lining wears down to a predetermined amount, the protruding part locks onto the anchor and the sliding of the support part is suppressed, so that the center part to the upper end part of the lining is accelerated to wear against the subsequent braking operation.
As a result, in the later stages of use, the entire lining can be worn almost uniformly. Replace the shoe when the lining shows approximately even wear.

〔Example〕

Hereinafter, embodiments of this invention will be described with reference to the drawings.

Figures 1 and 2 show one embodiment of this invention. In the figure, reference numeral 1 indicates a shoe of a leading trailing brake, and a lining 4 having a substantially uniform thickness L in the circumferential direction on the outer circumferential surface (fall-off polishing is initially performed to stabilize initial effectiveness). ) is fixed thereto, and has an arcuate rim 3 with a web 2 formed on its inner peripheral surface. The side surface of the lower end of this web 2 forms a support portion 2a that slidably abuts on one side surface of an anchor 5 fixed to a bucking plate (not shown), and the side surface of the upper end of the web 2 forms a support portion 2a that slidably abuts on one side surface of an anchor 5 fixed to a bucking plate (not shown), and the side surface of the upper end of the web 2 forms a support portion 2a that is slidably abutted on one side surface of an anchor 5 fixed to a bucking plate (not shown), and the side surface of the upper end of the web 2 is attached to a wheel cylinder (not shown), etc. The input section 2b receives the action of the expanding means of
is formed. Arrow A indicates the rotation direction of a brake drum (not shown), and shoe 1 is the leading shoe.

A protruding part 2c is formed near the support part 2a of the web 2 so as to protrude substantially in the horizontal direction.
The protruding portion 2c is formed at the lower end of the web 2 and at the upper end of the support portion 2a, and is formed on the anchor 5 in the initial state of assembling the shoe 1 to the drum brake.
A predetermined gap δ is formed between the top surface and the top surface. This gap δ is set to about 1/2 of the thickness L of the lining 4, and the protrusion 2c is locked to the anchor 5 when the anchor 5 side of the lining 4 is worn out by a predetermined amount, that is, about half its thickness. I'm starting to do that.

Next, the effect will be explained.

FIG. 2A shows the shoe 1 at its initial stage of use, and the lining 4, whose thickness L is substantially uniform in the circumferential direction, slides almost evenly onto the inner circumferential surface 16 of the brake drum.

FIG.
The wear is greater than that on the b side, and the shoe 1 is lowered in accordance with the amount of wear. Lining 4 like this
As the shoe 1 gradually descends following the uneven wear of the
gradually increases. Due to the repeated action of the brake, the wear of the lining 4 increases, and the vicinity of the anchor 5 of the lining 4 wears to a predetermined amount, that is,
When the lining 4 is worn to about 1/2 of the thickness L, the protrusion 2c fills the gap δ and locks onto the upper corner of the anchor 5. After that, the contact point P of the support portion 2a is fixed.

FIG. 2C shows the later stage of use of the shoe 1. The shoe 1 is used for braking with its protrusion 2c locked to the upper corner of the anchor 5, and the shoe 1 does not descend, so the lining 4 The input portion 2b is in strong sliding contact with the inner circumferential surface 16 of the brake drum from the center thereof, and wear in this portion is increasing. As a result, in the later stages of use of Shoe 1, lining 4
This results in almost uniform wear throughout. When the entire lining 4 becomes almost uniformly worn, replace the shoe 1.

[Effect of idea]

As understood from the above explanation, according to this invention, in the drum brake shoe,
By employing a simple configuration, substantially uniform wear can be achieved over the entire lining of the shoe, resulting in the practical effect of significantly increasing the service life of the shoe.

[Brief explanation of drawings]

Figures 1 and 2 show one embodiment of this invention.
2A, 2B and 2C are diagrams for explaining the operation, FIG. 3 is a diagram showing a conventional shoe, and FIG. 4A, RO and C are diagrams for explaining the same operation, respectively. DESCRIPTION OF SYMBOLS 1...Shu, 2...Web, 2a...Support part, 2b...Input part, 2c...Protrusion part, 3...Rim, 4...Lining, 5...Anchor.

Claims (1)

[Scope of utility model registration request] It has an arc-shaped rim with a lining fixed to its outer circumferential surface and a web formed on its inner circumferential surface, and the side surface of the lower end of the web forms a support part that slidably abuts on an anchor fixed to a bucking plate. 1. A shoe for a drum brake, characterized in that a protrusion is formed integrally with a web at an upper end of the support portion to be engaged with the anchor when the lining is worn out by a predetermined amount.